A Chicago insurance executive might seem like one of the last people who'd be opening a letter with this succinctly chilling message: "You have been targeted for terrorist attack."

But that's what happened last year, when a top official at Marsh USA Inc. was informed that he and his company's employees had landed in the crosshairs of an extremist animal rights group. The reason? Marsh provides insurance for one of the world's biggest animal testing labs.

"If you bail out now," the letter advised, "you, your business, and your family will be spared great hassle and humility."

That letter — and the harassment campaign that followed, after Marsh declined to "bail out" — was another shot fired by Stop Huntingdon Animal Cruelty (SHAC).

This British-born group, now firmly established in the United States, is waging war on anyone involved with Huntingdon Life Sciences, which tests drugs on approximately 70,000 rats, dogs, monkeys and other animals each year. In the process, SHAC is rewriting the rules by which even the most radical eco-activists have traditionally operated.

In the past, even the edgiest American eco-warriors drew the line at targeting humans. They trumpeted underground activists' attacks on businesses and laboratories perceived as abusing animals or the environment — the FBI reports more than 600 incidents, causing $43 million in damage, since 1996.

But spokespeople for the two most active groups in the U.S., the Animal Liberation Front (ALF) and the Earth Liberation Front (ELF), have always been quick to claim that their underground cells have never injured or killed any people.

Since 1999, however, members of both groups have been involved with SHAC's campaign to harass employees of Huntingdon — and even distantly related business associates like Marsh — with frankly terroristic tactics similar to those of anti-abortion extremists.

Employees have had their homes vandalized with spray-painted "Puppy killer" and "We'll be back" notices. They have faced a mounting number of death threats, fire bombings and violent assaults. They've had their names, addresses and personal information posted on Web sites and posters, declaring them "wanted for collaboration with animal torture."

When cowed companies began responding to the harassment by pulling away from Huntington, many radical environmentalists cheered — even when SHAC's actions clearly went over the "nonviolent" line.

Still, the ELF and ALF insist that they remain dedicated to what their spokespeople describe as nonviolent "economic sabotage," such as tree-spiking and arson. They vigorously deny the label that increasingly sticks to them: "eco-terrorist."

Spokespeople continue to chant the public-relations mantra that the ALF's David Barbarash invoked again on National Public Radio this January: "There has never been a single case where any action has resulted in injury or death."

SHACs escalating violence is not unique. North America's most active and widespread eco-radicals — the ELF and ALF took credit for 137 "direct actions" in 2001 alone — have clearly taken a turn toward the more extreme European model of activism. The rhetoric has begun to change along with the action.

Reached by the Intelligence Report, SHAC-USA's Kevin Jonas — a former ALF spokesman — was unusually frank about the lengths to which the new breed of activists will go.

'Igniting the Revolution' The far left has long been skirting the edge. In the 1980s, the standard-bearer of the movement was EarthFirst!, a radical group inspired by the novels of Edward Abbey, who romanticized a life of "monkey-wrenching," or sabotage, to protect the environment from rapacious corporations and developers.

Using the model of "leaderless resistance" long advocated by white supremacist tactician Louis Beam — small, independent underground cells carrying out actions, with no hierarchy for law enforcement to go after — EarthFirst! brought "direct action" to the forefront of the environmental movement.

The most controversial of EarthFirst! techniques was tree-spiking, which involved pounding metal spikes into trees to prevent them from being cut or milled into lumber. Typically, tree-spikings were accompanied by warnings designed to cut down on the possibility of injuring or killing timber workers.

But timber companies pointed out that some of the spikes would remain in trees long after the warnings had been forgotten, and said the technique put loggers and sawmill workers at risk of severe injury or even death. Such tactics resulted in the first references to environmentalists as terrorists.

Responding to criticism in the early 1990s, EarthFirst! members began to ponder a more moderate approach. This did not sit well with radicals, who left to found the ELF in Brighton, England, in 1992.

In its video, "Igniting the Revolution," the ELF says it realized "that to be successful in the struggle to protect the Earth, more extreme tactics must be utilized. Thus the Earth Liberation Front was born."

Coming to America It wasn't until 1998, when one of the ELF's underground cells burned down a major part of a new ski resort near Vail, Colo., that the group became a household name. The fire caused a whopping $12 million in damage and put eco-radicalism back in the headlines.

But news reports failed to note this was not a homegrown movement. The ELF, in fact, is an outgrowth of the European animal-rights movement more than American environmentalism. Its closely linked predecessor, the ALF, got its start in Britain in 1976 before crossing the Atlantic Ocean.

And while U.S. environmental activists still have a largely positive image, with the Sierra Club's peaceful lobbying efforts setting the tone in most people's eyes, activists of the British ALF and its continental cohorts have given the European movement a very different reputation.

Eco-activists there are seen by many as dangerous and reckless criminals — and they often live up to the billing, as the SHAC campaign (along with letter bomb attacks that have maimed one secretary and injured a furrier and his 3-year-old daughter) so vividly demonstrates.

In February 2001, Huntingdon's managing director in Great Britain, Brian Cass, was badly beaten outside his home by three masked assailants swinging baseball bats. Shortly after the attack, British animal rights activist David Blenkinsop, a friend of SHAC-USA's Kevin Jonas, was arrested and sentenced to three years in prison for the assault.

At around the same time, Andrew Gay, Cass' marketing director, was attacked on his doorstep with a spray that left him temporarily blinded, writhing on the ground in front of his wife and young daughter.

Ronnie Lee, one of the British founders of the ALF, applauded the beating of Cass. "He has got off lightly," Lee said. "I have no sympathy for him."

Joining in the jubilation were some American eco-radicals.

"If it happens and it works," Last Chance for Animals boss Chris DeRose said of attacks like the Cass beating, "then that's great."